Influence of laser heat input on weld zone width and fatigue performance of Ti-6Al-4V sheet

2020 ◽  
Vol 262 ◽  
pp. 114699 ◽  
Author(s):  
P.M. Mashinini ◽  
D.G. Hattingh
Keyword(s):  
Heat Input ◽  
Weld Zone ◽  
Fatigue Performance ◽  
Zone Width ◽  
Laser Heat

Forming Behaviour at Elevated Temperature of a Laser Heat-Treated AZ31 Magnesium Alloy Sheet

2018 ◽  
Vol 941 ◽  
pp. 1270-1275
Author(s):  
Donato Sorgente ◽  
Gianfranco Palumbo ◽  
Alessandro Fortunato ◽  
Alessandro Ascari ◽  
Ali Arslan Kaya
Keyword(s):  
Magnesium Alloy ◽  
Heat Input ◽  
Elevated Temperatures ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Dome Height ◽  
Magnesium Alloy Sheet ◽  
Laser Heat ◽  
Az31 Magnesium Alloy Sheet ◽  
Forming Behaviour

The tailoring of mechanical and technological properties of the initial material in sheet metal forming has been widely investigated and successfully applied. The benefits of such an approach can be found in the improvement of both the post-forming performances of the manufactured component and the forming process capabilities. Different strategies can be found and most of them involve a microstructural alteration by a selective heat source (e.g. laser, induction, UV light). The use of aluminium alloys combined with these strategies has been extensively investigated, while magnesium alloys are almost not yet considered from this viewpoint. In this work, we investigated the effect of a selective laser heat treatment on an AZ31 magnesium alloy sheet. After laser heat treating a single track in the centre of a blank with different heat input values, bulge tests at elevated temperatures were conducted. The dome height evolution was continuously acquired during the tests and differences between the untreated specimen and the laser treated ones have been characterized. The effect of the laser treatment was evaluated also in terms of thickness distribution of the formed specimens. A thickness discontinuity was found along the treated specimens in the transition zone between the treated and the untreated material. Results highlighted that an effective change in the forming behaviour can be induced in the treated zone depending on the laser heat input. It has thus been shown that this approach can be employed for tailoring the magnesium alloy blank properties prior to the gas forming at elevated temperatures.

scholarly journals Material Flow Visualization of Dissimilar Friction STIR Welding Process Using Nano-Computed Tomography

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Xun Liu ◽  
Sheng Zhao ◽  
Kai Chen ◽  
Jun Ni
Keyword(s):  
Computed Tomography ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Volume Fraction ◽  
Weld Zone ◽  
Process Conditions ◽  
Rotating Speed ◽  
Friction Stir ◽  
Small Tool

In this study, the friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel is analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-computed tomography (nano-CT) is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset, and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.

scholarly journals A Study on Vertical Upward Welding of Dissimilar Material and Thickness of Thin Plates Using Novel TIG Welding Process

2019 ◽  
Author(s):  
Ngo Huu Manh ◽  
Nguyen Van Anh ◽  
Murata Akihisa ◽  
Hideno Terasaki
Keyword(s):  
Base Metal ◽  
Heat Input ◽  
Weld Zone ◽  
Welding Process ◽  
Welding Current ◽  
Tig Welding ◽  
Dissimilar Material ◽  
Thin Plates ◽  
Welding Defects ◽  
Welding Position

A study about influence of heat input on welding defects in vertical upward welding position for dissimilar material and thickness using a new variation of TIG welding torch is done with support of advanced inspection methods SEM and EBSD. With vertical upward welding position, control heat input plays an important role to keep the weld stabilization without defects. On the other hand, TIG welding process using a conventional TIG torch (conventional TIG welding process) has low efficiency and it is difficult to control heat input with high accuracy. So, it is considered that using conventional TIG torch is still a challenge for welding thin plates. In this case, a new variation of TIG torch has been developed. This torch used a constricted nozzle to improve plasma arc characteristics. As a result, it can control efficiently the heat input to prevent the excessive or insufficiency for joining thin sheets. For evaluation of welding quality, advanced examination methods SEM and EBSD were applied to directly observe the welding defects. From the results, the formation mechanism of blowhole inside weld zone in case of welding dissimilar material and thickness was discussed. It is pointed out that when sufficient welding current, the change from weld zone to base metal is uniform, no welding defects such as blowhole was seen. However, in case of low welding current, the thinner base metal is insufficient fusion and the change between weld zone and base metal is not uniform. The blowhole was observed at SS400 material side.

Effect of Welding Heat Input on Grain Size and Microstructure of 316L Stainless Steel Welded Joint

2013 ◽  
Vol 331 ◽  
pp. 578-582 ◽  
Author(s):  
Li Chan Li ◽  
Meng Yu Chai ◽  
Yong Quan Li ◽  
Wen Jie Bai ◽  
Quan Duan
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Heat Input ◽  
316L Stainless Steel ◽  
Weld Zone ◽  
Welding Process ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding ◽  
Average Grain Size ◽  
Arc Welding Process

Influences of heat input on the microstructure and grain size of shielded metal arc welded 316L stainless steel joints were studied. Three heat input combinations were selected from the operating window of the shielded metal arc welding process and welded joints made using these combinations were subjected to microstructural evaluations so as to analyze the effect of thermal arc energy on the microstructure and grain size of these joints. The results of this investigation indicate that the microstructure of the weld zone and the fusion zone are austenite and a small amount of ferrite while the microstructure of the heat affected zone (HAZ) are austenite and a small amount of MC type carbides, and it can be seen that the amount of ferrite in the weld zone decreases with heat input. For the joints investigated in this study, the average grain size in the HAZ increases with heat input.

Microstructure and Mechanical Properties of Laser Welded Lap Joints of Ti-6Al-4V Alloy

2011 ◽  
Vol 311-313 ◽  
pp. 2375-2378 ◽  
Author(s):  
Yong Zhao ◽  
Jian Huang ◽  
Ying Zhao ◽  
Yi Xiong Wu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Weld Joint ◽  
Welding Speed ◽  
Heat Input ◽  
Laser Power ◽  
Weld Zone ◽  
Lap Joints ◽  
Lap Joint ◽  
The Difference

Microstructures and mechanical properties of welded Ti-6Al-4V alloy lap joints are discussed under different parameter conditions of laser welding. The results reveal that the fusion zone consists mainly of acicular α＇martensite. The shear strength of the lap joint reaches a maximum of 836MPa at a laser power of 4kW and welding speed of 2.3m/min. When the laser power is 4kW and the welding speed is 2.1m/min, microstructures of weld joint become coarse and the shear strength falls to 736MPa. The microhardness value in the weld zone is the highest and it gradually reduces from the weld center to base metal due to the difference of microstructure. When the weld heat input is constant, larger laser power has resulted in growth of the grain and the decrease of shear strength and microhardness of lap joints.

scholarly journals Effect of laser heat input on the properties of cladding layer

2021 ◽  
Vol 1965 (1) ◽  
pp. 012085
Author(s):  
Pengcheng Che ◽  
Haiyan Dai ◽  
Huaizhi He ◽  
Guangfu Cheng ◽  
Jingchao Zhou ◽  
...  
Keyword(s):  
Heat Input ◽  
Cladding Layer ◽  
Laser Heat

Research on Intergranular Corrosion Behavior of Welded Joints of Nuclear Grade Stainless Steel

2014 ◽  
Vol 809-810 ◽  
pp. 390-394
Author(s):  
Meng Yu Chai ◽  
Can Liang ◽  
Dong Dong Wang ◽  
Quan Duan ◽  
Zao Xiao Zhang
Keyword(s):  
Stainless Steel ◽  
Welded Joints ◽  
Heat Input ◽  
Intergranular Corrosion ◽  
Weld Zone ◽  
Base Material ◽  
Delta Ferrite ◽  
316Ln Stainless Steel ◽  
Welding Heat Input ◽  
Micro Structures

The intergranular corrosion (IGC) behaviors of welded joints of 316LN stainless steel with different welding heat input were investigated in this study. The boiling nitric acid method was chosen to provide the IGC environment. The corrosion rates of different specimens were studied and the micro-structures of each zone (base material, heat affected zone and weld zone) were analyzed in detail. The results show that welding heat input affects IGC resistance remarkably and low welding heat input can reduce the IGC tendency. The IGC test can be divided into three stages, i.e. the initial corrosion stage, stable corrosion stage and rapid corrosion stage. The IGC resistance of WZ for 316LN stainless steel is better than that of BM and HAZ due to the beneficial role of delta ferrite.

Resistance spot weldability of TBF steel sheets with dissimilar thickness

2020 ◽  
Vol 117 (6) ◽  
pp. 620
Author(s):  
Imren Ozturk Yilmaz ◽  
Abdullah Yasin Bilici ◽  
Hakan Aydin
Keyword(s):  
Liquid Metal ◽  
Heat Input ◽  
Indentation Depth ◽  
Crack Depth ◽  
Weld Zone ◽  
Liquid Metal Embrittlement ◽  
Tensile Shear ◽  
Steel Sheets ◽  
Weld Current ◽  
Dissimilar Thickness

This paper presents an experimental study on weldability of TBF steel sheets with dissimilar thickness. Nominal thickness of TBF sheets were 0.95 and 1.55 mm. Optical microscope was used to observe the cracks formed in the weld zone. The indentation depths were determined by ultrasonic technique. Tensile shear tests were applied to the welded specimens in order to determine the mechanical properties. Higher weld current and time resulted in higher nugget size and indentation depth. This increase in nugget size and indentation depth with increasing of weld current and weld time was almost linearly. The liquid metal embrittlement crack sensitivity in the HAZ was very high on TBF spot welds. The liquid metal embrittlement cracks were much deeper and wider along the weld periphery regions compared to the nugget regions. These cracks were occurred easily with a higher heat input and the crack depth increased almost linearly with increasing of heat input. Weld strength of the specimens was governed by crack formation in the HAZ. Lower weld currents and weld times resulted in higher tensile shear properties. The highest tensile shear load (18.50 kN) and energy absorption (37.5 J) were achieved at 6 kA for 20 cycles. This weld exhibited interfacial failure mode.

Surface hardening characteristics of press die cast iron and plastic mold steel according to laser heat input

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040029
Author(s):  
Moo-Keun Song ◽  
Jong-Do Kim
Keyword(s):  
Heat Treatment ◽  
Cast Iron ◽  
Heat Input ◽  
Surface Hardening ◽  
Surface Heat ◽  
Mold Material ◽  
Laser Heat ◽  
Die Cast ◽  
Laser Heat Source ◽  
Plastic Mold

In this study, the surface heat treatment of mold materials was performed using a high-power laser heat source and surface hardening characteristics were investigated. Laser surface heat treatment is a hardening method in which a surface is heated using high-density energy and self-quenched through rapid cooling. Hence, the heat input during laser heat treatment is important. The heat input for the surface hardening of each material was compared, and it was found that the heat input for each mold material was different. Additionally, die cast iron has higher thermal conductivity compared to mold steel, resulting in a larger heat input during heat treatment.

The Effects of Temper Bead Welding Technique on Weld Integrity for In-Service Welding of Carbon Steels

2012 ◽  
Author(s):  
K. Meszaros ◽  
C. Vrolyk ◽  
J. Pepin ◽  
M. Yarmuch ◽  
T. Mah-Paulson
Keyword(s):  
Heat Input ◽  
Weld Zone ◽  
Carbon Steels ◽  
Steel Plates ◽  
Welding Parameter ◽  
Welding Parameters ◽  
Shielded Metal Arc Welding ◽  
Burn Through ◽  
Welding Technique ◽  
Repair Techniques

The maintenance of pipeline infrastructure is a significant integrity consideration for the pipeline industry. Employing traditional repair techniques, whereby to conduct repairs when the pipeline is shut-down and drained, can result in significant losses to revenue and production. There is industry demand for repair techniques that allow both scheduled and emergency ‘in-service’ weld repair techniques to be developed. As a result, in-service welding with the temper bead technique is becoming increasingly common for repair operations. During in-service welding, the two most prevalent metallurgical concerns are burn-through and hydrogen induced cracking (HIC). The risk of burn-through can be limited through appropriate welding parameter and heat input control during welding. The temper bead welding technique utilizes special bead placement to ensure appropriate heat flow throughout the weld zone to metallurgically improve resistance to HIC. In this study, a series of shielded metal arc welding (SMAW) coupons were produced on 0.250″ thick carbon steel plates subjected to water-cooling. Single and double-layer deposits were made. The second layer tempering bead heat input was purposely varied from plate to plate. The first layer of the welds were all performed using similar welding parameters, so the “tempering” effect from the second weld layer on the metallurgical properties of the resultant welds could be examined. To further expand the understanding of important procedural variables for in-service welding applications, this study investigates the effect of welder technique on the weldment properties achieved during temper bead welding.

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